Loop antenna



1949 v H. VAN BILLIARD ,7

LOOP ANTENNA Filed May 9, 1946 Fi gmlllllllIIIllllllllllllllllllilllllil Inventor".

Lewis HV-an Billiard,

' His Attorney.

Patented Dec. 27, 1949 Lewis H. Van Billiard, Newton, .(Ionm, asslgnorto General Electric Company, a. corporation 101' New York ApplicationMayB, 1946, Serial No. 668,350 Claims. (Cl. 250 33.67)

My invention relates to radio receivers and, in particular, to loopantennas for use in such receivers. It has for one of its objectsto'provide a new and improved loop antenna structure which is easilymanufactured in quantities at low cost.

A further object of my invention is to provide a new and improvedloopantenna structure which is rugged and which is not subject tovibration due to the presence of a loud speaker in a'radio cabinet.

It is a still further object of my invention "to provide a. new "andimproved loop antenna structure for a radio receiver which does notrequire any additional space or extra components in the receivercabinet.

One of the features of my invention consists in utilizing theba'c'kpanel of a radio'receiver to support a'lo'op antenna and winding thisloopantenna'as a continuous-rectangular conductor having adjacent legssupported on opposite sides of the back panel.

The novel features which .I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization and method of operation,together with further objects and advantages (thereof, may bestbeunderstood by reference to the accompanying drawings in which Fig. 1represents a, portion of a radio cabinet which includes 'a loop antennaconstructed in accordance with my invention, and

iacent legs of the panel are disposed on opposite sides of that panel.

In winding the antenna on the panel 3, the conductive strip is started,for example, at the upper left-hand corner of the "rear panel at ahorizontal notch 8 and extends along the outer surface of the panel tothe upper of the inclined notches 6 at the lower left-hand corner of thepanel. At that point, the strip makes a 45 bend and proceeds across therear of the panel to the upper of the notches 6 in the lower right-handcorner. After another 45 bend, the strip passes across theouter surfaceof the panel to the lower of the notches "in the upper right-handcorner. The winding progresses in this fashion alternating on the innerand outer surfaces of the panel until the "winding is terminated in thevertical notch 9 in the upper left-hand corner. A .rear view of theupper left-hand corner is shown in Fig. 2 to illustrate how the strip isbent over the edge of the panel at the notches '8 and 9 at the 7beginning and termination of the winding, re-

specti-vely, and'how the 45 bend is made at the notches "6. Furthermore,the antenna winding is 5 preferably secured to the back panel 3 byeither Fig. 2 is an enlarged perspective *view of a portion of theantenna of Fig. 1.

Referring to "Figs. 1 and '2 jointly, I have'there illustrated a rearview of a'radio cabinet *I having a radio receiver chassis 2 mountedtherein. Arranged behind the chassis 2 15a rear panel .3 which isattached 'to the cabinet by means of ;a plurality of screws 4. The panel3 may be formed of any suitable insulating material, such as a pressedfiber board, and supported thereon is a loop antenna 5.

The rear panel 3 is cut away at its four corners and in each cornerthere is provided ,a plurality of notches 6 which are inclined .at .an.angle to the edges of the panel. Each of the notches 6 is separatedJ95? a tongue 1 formed :by a portion of the rear panel .3 which projectsbeyond the plane of the notches \6. The antenna 15 comprises :an endless:strip of flexible conducting material, "for "example, .a strip ofcopper which woundaslacontinuous windingbetween the notches B andadjacent corners of the panel .3. Furthermore, at each of the corners,the antenna '5 changes from one side {of the rear panel 3 to'theopposite side. In this fashion .the portions-or the conductive materialof the antenna which extend along'adcementing the conductive strip tothe panel or in any other suitable fashion. 'Thus, the strip may haveadhesive applied to one side thereof prior to the winding operation .50that it adheres to the panel as it is wound thereon. Alternatively, theadhesive maybe applied atthe time the strip is wound on the panel. Theadhesive may besuchthat heating by means of a heating plate is requiredto warm the adhesive material to obtain fastening of the strip to thepanel. Alternatively, the warming may be obtained by passing currentthrough the conductive strip and thereafter applying pressure to bringthe strip into intimate contact with the panel. .As another alternative,the conductive strip may be wound on the rear panel and then coveredwith a paper which is attached to the rear panelinany suitable manner,.as by cementing.

- Connections to the antenna winding maybe made at any one of thecorners and, inthe {drawings, are shown as being made at the points ill,

' H, 12, Thus, if the radio receiver is to be .used

for reception on both the broadcast and short wave hands, a single loopmay provide suiiicient pick-=up or energy for the broadcast band,espedaily if the receiver is of the low impedance in- 1 put type, suchas a receiver employing permeability tuning. Accordingly, such anantenna arrangement is provided by connection between the points 1-D andl I. However, for short wave, it may bo-desirable to have two or moreturns and such connection is effected by connection between points andI2. The points Ill-l2 may be connected by means of a cable I3 to apolarized plug M which is adapted to be inserted in a suitablereceptacle provided in the chassis 2.

On small receivers, the panel 3 may be imperforate and sufficientventilation for the receiving equipment provided by the cut-awayportions at the four corners thereof. However, for larger receivingapparatus, it may be desirable to provide a plurality of openings 15 atthe lower portion of the rear panel and an opening IS in the upperportion of the rear panel to facilitate flow of air through the chassisand receiving apparatus to provide sufficient cooling thereof. Likewise,additional openings I1, l8 may be provided to permit access to thechassis for tuning or switching of the receiver circuits without removalof the rear panel.

While in the foregoing I have described and illustrated the antenna asbeing rectangular in form, it is obvious that the rear panel 3 may bepolygonal and have any number of edges. In such a case, the antenna 5 iswound as a continuous conductive member being placed on alternate sidesof the panel for adjacent legs of the polygon.

An important advantage of my improved antenna structure is that it isboth simple and low in cost to manufacture. Thus, the copper strip maybe rigidly secured to the rear wall by a simple winding operation.Furthermore, the rear panel may be easily stamped by any suitablepunching operation to provide a form for winding the antenna thereon.

. Another important advantage is that, with the winding formed of spacedturns and cemented or otherwise secured to the rear panel, all tendencyto vibrate due to reaction from the loud speaker of the receiver iseliminated.

While I have shown a particular form of my invention, it will of coursebe understood that I do not wish to be limited thereto since differentmodifications may be made Without departing from the spirit and scope ofmy invention, and I contemplate by the appended claims to cover any suchmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A radio receiving system, comprising, a cabinet, a radio receiverchassis mounted in said cabinet, said cabinet including a rear panelfixed thereto and serving therewith to enclose said radio receiverchassis, said rear panel having a plurality of notches formed in'each ofthe corners thereof, a loop antenna mounted on said panel, said antennacomprising a broad, flat strip of solid flexible conducting materialwound in a continuous coil in the plane of said panel about the marginthereof, said material alternating between the front and rear sides ofsaid panel, said alternations occurring at the corners of said panel,and said notches serving respectively as supports for successive turnsof said material.

2. A radio receiving system, comprising, a cabinet, a radio receiverchassis mounted in said cabinet, said cabinet including a rear panelfixed thereto and serving therewith 'to enclose said radio receiverchassis, said rear panel being composed of electrical insulatingmaterial and having a plurality of notches formed in each of the cornersthereof, a loop antenna mounted on'said panel, said antenna comprising abroad, fiat strip of solid flexible conducting material wound in acontinuous coil in the plane of said-panel about the margin thereof,said material alternating between the front and rear sides of saidpanel, said alternations occurring at the corners of said panel, andsaid notches serving respectively as supports for successive turns ofsaid material.

3. A radio receiving system, comprising, a cabinet, a radio receiverchassis mounted in said cabinet, said cabinet including a rearrectangular shaped panel fixed thereto and serving therewith to enclosesaid radio receiver chassis, said panel having a plurality of notchesformed in each of the corners thereof, a loop antenna mounted on saidpanel, said antenna comprising a flat strip of solid flexible conductingmaterial wound in a continuous rectangular coil in the plane of saidpanel about the margin thereof, said material alternatingbetween thefront and rear sides of said panel, said alternations occurring at thecor ners of said panel, said notches serving respectively as supportsfor successive turns of I said material, and means adhesively connectingsaid conducting material to said panel. a

4. A radio receiving system, comprising, a cabinet, a radio receiverchassis mounted in said cabinet, said cabinet-including a rearrectangular shaped panel of non-conducting material fixed thereto andserving therewith to enclose said radio receiver chassis, the corners ofsaid panel having cut portions inclined at an angle to the edges of saidpanel, said panel further having a plurality of notches formed in saidout portions, a flat strip of solid flexible conducting material woundbetween adjacent of said corners to form a rectangular antenna windingin the plane of said panel about the margin thereof, the portions ofsaid conductor serving as adjacent sides of said rectangular windingbeing disposed on opposite.

sides of said panel, and said notches serving respectively-as supportsfor successive turns of said material.

5. A radio receiving system, comprising, a

cabinet, a radio receiver chassis mounted in said.

cabinet, said cabinet including a rear rectangular shaped panel ofinsulating material fixed thereto and serving therewith to enclose saidradio receiver chassis, the corners of said panel having cut portionsinclined at an angle to the edges of said panel, said panel furtherhaving a plurality of notches formed in said out portions, a fiat stripof solid flexible conducting material wound in a continuous rectangularcoil in the plane of said panel about the margin thereof, said fiatstrip alternating between the front and rear sides of said panel, saidalternations occurring at said corners, said notches servingrespectivelyas supports for successive'turns of said flat strip, andmeansadhesively connecting said strip to said panel.

LEWIS H. VAN BILLIARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,812,695 Harms June 30, 19311,826,437 Shapiro Oct. 6, 1931 2,215,422 Glerum Sept. 1'7, 19402,318,361 Bischofi 1 May 4, 1943 2,401,472 Franklin June 4, 1946 FOREIGNPATENTS Number Country Date 513,961 Great Britain Oct. 26, 1939 615,018France Dec. 28, 1926

